Virtual-reality head-mounted displays have wide applications in various fields, including engineering design, medical surgery practice, military simulated practice, and video gaming. For example, a user wears a virtual-reality head-mounted display integrated with audio headphones while playing video games so that the user can have an interactive experience in an immersive virtual environment. It may be difficult, however, for a user to properly adjust and comfortably wear the head-mounted displays and the integrated audio systems using the existing technology, which may negatively affect the user's experience.